Our objective is to develop and test new synthetic polyester polymers fabricated into bundles of microtubes, to be inserted lengthwise in injured mammalian spinal cords and other parts of the central and peripheral nervous system as potential guides that may encourage and orient axons regenerating into and across the damaged tissue. The main efforts will go into designing and fabricating the prosthesis, to be to be composed of tubes of about 50-100 micrometers caliber that would be biodegradable at controlled rates, nontoxic, non-antigenic, noncarcinogenic in themselves or their degradation products, that would be of appropriate tensile strength for surgical manipulation, and most important, would preferentially attract and guide regenerating nerve fibers. Among the technical problems to be solved will be to fabricate the microtubes by a solution casting or solvent spinning process, to avoid the use of potentially toxic chemical additives required by the more conventional extrusion or lamination processes. These properties will be assayed primarily in a newly developed, highly efficient and reproducible micro tissue culture system, and the more promising polymers will later be tested in living animals. The work of the past year has established that a number of newly synthesized polymers serve as satisfactory substrates for axonal growth in tissue culture. These substrates will be analyzed further in culture, and will now be fabricated into microfibers and tubes for testing in living animals.